U.S. Pat. Nos. 5,189,694 and 5,243,644 issued Feb. 23, 1993 and Sep. 7, 1993 respectively in the names of Stuart M. Garland et al, and are entitled "Telemetry Access Arrangement". These patents describe methods and apparatus for establishing suppressed ringing access to subscriber lines so that utility meters connected to the subscriber lines can be read without ringing telephone sets connected to the same subscriber lines.
According to the methods and apparatus described in U.S. Pat. Nos. 5,189,694 and 5,243,644, a telephone operating company provisions Utility Telemetry Trunks (UTT) between a telemetry server located at a central office of the telephone operating company and all terminating switches which serve subscriber lines to which utility meters are connected. Each terminating switch is programmed to provide normal ringing access to connections made via trunks other than the UTT and to provide suppressed ringing access for connections made via the UTT. For suppressed ringing service via subscriber carrier facilities, the terminating switch is programmed to provide a short burst of ringing--long enough to enable the subscriber line carrier to set up the connection, but too short to cause audible ringing of telephone sets connected to the subscriber line.
Unfortunately, the cost of provisioning UTT can be high enough to constrain the number of terminating switches and subscriber lines that can be accessed by the telemetry server.